It is generally known that vitamins are not very stable and degradation is to be observed for example on storage. This also applies to the so-called B vitamins, explicitly vitamin B12. For this reason, there have been very many studies on the topic of the stabilization of vitamins and of vitamin B12. A simple solution to this problem is for example separating the vitamin B12 from substances which promote its degradation. Thus, for example, JP200612486 describes 3 partial solutions in which individual partial formulations are present. Vitamin B12 is stabilized not only in liquid formulations, but also in tablets or granules, as described for example in EP416773. Most of the studies on the stabilization of vitamin B12 relate however to liquid formulations. Such solutions can also be used to fill capsules (FR1472901), or the solutions are freeze dried for further stabilization (JP63313736). Among the vitamin B12 solutions ready for use there are some stabilized by the addition of iron salts (FR1285213, GB902377). The solutions may likewise comprise EDTA (ethylenediaminetetraacetic acid, U.S. Pat. No. 2,939,821 or GB822127). Alkali metal salts or alkaline earth metal salts are also said to have a stabilizing effect on vitamin B12 (U.S. Pat. No. 2,566,123). Vitamins can also take place by use of amino acids (U.S. Pat. No. 2,748,054) or by cyclodextrins (JP4049239), as well as by ammonium sulphate (U.S. Pat. No. 2,778,771), by sodium iodide (JP41007474), potassium cyanide (GB692968), maleic acid (JP64011864), thiopropionic acid (U.S. Pat. No. 2,579,679), gluconolactone (ES247522), lecithins (JP55049313), urea (JP43010862) or else by fatty acid esters with cysteine (U.S. Pat. No. 2,662,048) or by antioxidants (DE25222187) and so-called chelating agents (WO97/31620). Even solutions in N-methylpyrrolidone DE3337304 are described, in which vitamin B12 is said to be stable. In some studies, vitamin B12 is stabilized through the use of polyvalent alcohols (JP2311417, JP63313736, JP05124967, FR1263794, JP04-235925, JP2000-319186 or HU150885). The use of alcohols for stabilizing vitamin B12 is proposed generally in JP2005247800, WO2005/094842, WO02/02145, BE576619 or JP02145521. US2005074443 describes long-chain alcohols for stabilizing vitamin B12. However, vitamin B12 itself is also used in turn to stabilize other substances (JP2001-048780, JP2005-015368).
Thus, in JP46-15320 propylene glycol is employed for isotonicity and benzyl alcohol as analgesic. The actual stabilization is achieved by dextran and gelatin (hydrophilic macromolecules). In JP45-011919, the alcohols propylene glycol, benzyl alcohol, mannitol or glycerol are described for stabilizing 5,6-dimethylbenzimidazolyl cobamide coenzyme.
A possible way of stabilizing vitamin B12 through the use of butanol has been found. Although JP2005247800 mentions alcohols for stabilizing vitamin B12, for example the chlorobutanol contained therein is unsuitable specifically for the solution used in this case and is, on the contrary, harmful. Likewise, the benzyl alcohol contained in JP46-15320 or JP45-011919 is distinctly disadvantageous for the formulation described herein, because benzyl alcohol cannot be metabolized by all animals (EMEA, Committee for veterinary medicinal products, summary report, benzyl alcohol, 1997) and formulations with benzyl alcohol therefore cannot be employed as widely as formulations with butanol.